In the conventional method of imparting crease resistance to a wool fiber by use of a chlorinating agent or an oxidizing agent, even if an attempt is made to restrict the action of the agent to the scale surface, the action reaches the cortex so long as the method is practised in an aqueous solution so that the oxidation permeates unlimitedly into the interior of the fiber and renders the interior of the fiber brittle and damaged. If the action is insufficient, the result also becomes inevitably insufficient. Even if the reaction is terminated at an intermediate stage or an organic oxidizing agent exhibiting its action is employed relatively slowly, it is not possible to restrict the degree of oxidation, and decomposed products during the oxidation again deposit onto the fiber surface and reduce the color fastness properties of the fiber. Thus, the conventional method is not free from various mechanical problems.
In the method which allows the animal fiber to first contain acids, so long as the method is carried out in an aqueous solution, the acids unlimitedly permeate into the interior of the fiber through the permeation canals of the moisture so that it becomes practically impossible to limit the oxidation to the surface of the animal fibers.
The method of the present invention accomplishes the modification of the animal fiber goods by the steps of first allowing limited portions of the scales on the surface of the animal fibers to adsorb a pro oxidizing-catalyst that promotes the oxidation decomposition by the chlorinating agent or oxidizing agent, then dipping the goods in the solution of the chlorinating agent or oxidizing agent, performing the oxidation while restricting the oxidation only to the surface portions of the animal fiber thereby to strip off only the scale portions upon which the oxidation acts, thus carrying out the treatment under such conditions that do not at all damage the cortex inside the fiber.
Though the surface of the wool fiber has an extremely high water repelling property, the water is likely to be adsorbed onto the endo cuticle at the edge portions. This fact is illustrated by the following literature:
(1) Kokusai Yomo Jimukyoku, 11-46, 1-chome, Akasaka, Minato-Ku, Tokyo-to, published on June 30, 1976, "Crimp, Wool and Tecnhiques", No. 33, p. 3-9, edited by Ryoji Nakamura, "Structure of epidermis cuticle layer of wool".